Method for enhancing the flavor and shelf life of food products

ABSTRACT

A processor (10) for processing food products, including those derived from animals such as catfish (12), includes a perforator (20) for perforating the membranes of the animal products. Fillets (22) are weighed by a scale (24) and analyzed for fat content by an analyzer (26). A vacuum tumbler (32) exposes the fillets (22) to both a partial vacuum created by vacuum source (44) and a hypotonic saline processing solution (48) partially filling the cylindrical drum (34) of the vacuum tumbler (32). A computer (28) provides central control of the processor (10). Processed fillets (50) may be weighed and analyzed for fat content, and then sorted and packaged for delivery. A sequence of process steps performed by the processor (10) may include feed-forward lines (120) or feedback lines (126) to prepare the vacuum tumbler (32) for processing or to initiate a re-tumble. The processing solution (48) may also be a hypotonic saline solution with selected amounts of an organic acid, such as ascorbic acid, and yeast.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/228,029filed Apr. 15, 1994, entitled "Method and Apparatus for Enhancing theFlavor and Shelf Life of Food Products," by Billy M. Groves, nowabandoned.

TECHNICAL FIELD OF THE INVENTION

This invention relates to processing food products generally and animalproducts specifically. This invention is more particularly directed to amethod and apparatus for enhancing the flavor and shelf life of foodproducts.

BACKGROUND OF THE INVENTION

The food processing industry is continually developing new approaches topreparing food products and particularly food items derived from animalproducts for human consumption. Generally, these approaches attempt toimprove the overall consistency and quality of food products deliveredto the consumer. In particular, food processors adopt various methodsand systems to improve the flavor, shelf life, appearance, and nutritionof food products.

One approach to processing food products, and animal products inparticular, places the animal product in a tumbler filled with a salinesolution. The ham processing industry uses a tumbler to dramaticallyincrease the water content of ham, sometimes as much as one hundredpercent from its pre-tumbling weight. Another approach utilizes atumbler partially evacuated and filled with a saline solution foralternately exposing the animal products to the saline solution andpartial vacuum. The hydration achieved using a vacuum tumbler issignificantly lower than the hydration achieved when processing hamsusing a conventional tumbler.

Overall consistency and quality of certain fish products may be improveddramatically by similar food preparation processes. In particular, theprocessing of catfish in a tumbler may result in a reduction in the"off-flavor" problem that historically has limited the expansion of thecultured catfish industry. It is estimated that ten percent of anyharvest of "good" catfish is off-flavor. During the late summer as muchas eighty percent of the available pond product is sufficientlyoff-flavor to interfere with commercial use. At least one source of theoff-flavor in catfish tissue is geosmin (C₁₂ H₂₂ O), which is a volatilealcohol deposited by the metabolic process of the fish in the lipidfraction of the body. Several previous approaches, including tumblingand vacuum tumbling, have attempted to remove geosmin from catfishtissue to enhance flavor, reduce the overall fat content of the fish,and improve its shelf life.

Previous processing systems have experienced some limited success inenhancing the overall quality and consistency of animal products. Theseprevious approaches, however, have not adequately identified andextracted the major components leading to low quality animal productsand bacterial contamination. Furthermore, specific approaches in thecatfish industry have not sufficiently solved the off-flavor problem ofcultured catfish, especially the off-flavor present in larger and higherfat content fish caught during the late summer. The disadvantages ofprior methods and systems for processing animal products have severelyimpaired the expansion of the cultured catfish industry.

SUMMARY OF THE INVENTION

In accordance with the present invention, the disadvantages and problemsassociated with previous methods and systems for processing foodproducts, and in particular animal products, have been substantiallyreduced. The present invention improves on previous approaches byperforating the tissue of the animal products before vacuum tumbling. Inaddition, the present invention utilizes: (i) a hypotonic salinesolution to enhance osmosis into the cellular structure, (ii) an organicacid additive to neutralize the chemicals associated with the off-flavorproblem, and (iii) a yeast product to enhance the flavor of the animalproduct.

In one embodiment of the present invention a method for enhancing theflavor of animal products includes perforating the membranes of theanimal products. The animal products are loaded into a vacuum tumblerand the vacuum tumbler is filled to a predetermined level with aprocessing solution. Air from the tumbler is withdrawn to create apartial vacuum. The tumbler is rotated for a predetermined time toexpose the animal products to the processing solution and the partialvacuum. The animal products are removed from the tumbler after thepredetermined time and packaged.

In accordance with another aspect of the present invention, a system forenhancing the flavor of animal products includes a perforator forperforating the animal products. A vacuum tumbler is adapted to receive(i) the animal products and (ii) a fluid mixture including water andsodium chloride. A vacuum source connected to the tumbler creates apartial vacuum. A motor connected to the tumbler rotates the tumbler.Ribs, attached to an internal wall of the tumbler, extend substantiallyparallel to the axis of rotation of the tumbler. The ribs support theanimal products and expose the animal products to the fluid mixture andthe partial vacuum as the tumbler rotates.

In accordance with another aspect of the present invention, a solutionfor processing animal products in a vacuum tumbler includes: (i) waterin an amount approximately equal by weight to the animal products, (ii)sodium chloride in an amount no more than 0.9 percent of the weight ofthe animal products, (iii) an organic acid in an amount sufficient toadjust the pH of the solution to a value of less than 8.0 but preferablyfrom 4.5 to 5.5, and (iv) yeast in an amount of approximately 0.1percent of the weight of the animal products.

One technical advantage of the present invention includes enhancedappearance and taste of the processed animal products. The presentinvention enhances taste of the animal products by removing chemicalscontributing to the off-flavor problem. The combination of perforatingand vacuum tumbling in a processing solution also produces animalproducts with a fresher appearance and a more pleasant odor.

Another important technical advantage of the present invention is areduction in total fat content of the processed animal products.Together with the extraction of chemicals contributing to the off-flavorproblem, the same mechanism also reduces the fat content of the animalproducts. The present invention also reduces cholesterol andtriglycerides.

Another important technical advantage of the present invention isimproved shelf life of the processed animal products. The processingpromotes bacterial lysis which greatly diminishes the bacteria count inthe animal products and improves its shelf life.

Another important technical advantage of the present invention includesperforating the membranes of the animal products to assure a moreuniform and extensive exposure to the processing solution and partialvacuum. The perforations allow greater penetration of the processingsolution to extract off-flavor chemicals, reduce the fat content, andlower the bacteria count without sacrificing the appearance andintegrity of the cellular membrane.

Another important technical advantage of the present invention is aprocessing system including a vacuum tumbler and a variety of sensorsunder the central control of a computer. In particular, the motor andvacuum source of the vacuum tumbler may be controlled by a computer inresponse to data received from a scale for weighing the animal productsand an analyzer for measuring the fat content of the animal products.The processing time, processing rate, vacuum level, and amount andcomposition of the processing solution may be adjusted based onmeasurements of the unprocessed or processed animal products.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and forfurther features and advantages, reference is now made to the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates the processing steps and components of an animalproducts processor constructed in accordance with the present invention;and

FIG. 2 is a flow diagram illustrating the sequence of process steps andinformation flow of the processor of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The present invention and its advantages are best understood byreferring to FIGS. 1 and 2 of the drawings, like numerals being used forlike and corresponding parts of the various drawings.

The present invention contemplates a method for processing such foodproducts as those derived from animal products and a system for carryingout the method. The present invention is described with reference toprocessing catfish, but other food products may be processed with minorvariation and similar success. For example, the present invention hasbeen used with success on shrimp, chicken, beef, and venison. Shrimp hasbeen extensively processed with excellent improvement in flavor andcomplete cleaning of the "sand line" or "vein" typically found inshrimp. The present invention may also be extended to the processing ofsoy meal, since geosmin which contributes to the off-flavor problem incatfish is also known to cause the "earthy" smell in the soybean.

Now referring to the processing of catfish, it is believed that thepresent invention attacks the off-flavor problem in the catfish tissueby removing, among other materials, geosmin (C₁₂ H₂₂ O), the storagesource of at least one chemical causing the persistent and unpleasanttaste. Geosmin is a volatile alcohol deposited by the metabolic processof the fish in the lipid fraction of the body. The present inventionuses several mechanical and chemical aspects to extract geosmin andremove other off-flavor materials in catfish.

One mechanical aspect of the present invention is vacuum tumbling, whichenhances cleaning and exposes greater cellular membrane area to theextraction process. During vacuum tumbling, the catfish retains adesired percentage of the processing solution to improve overallappearance and taste. Vacuum tumbling also contributes to bacteriallysis which improves the shelf life of the catfish. Another mechanicalaspect of the present invention is tissue perforation, especially of themembrane covering areas, which assures uniform and more extensiveexposure of the catfish to vacuum processing.

Several chemical aspects of the present invention also enhance thequality and flavor of the catfish, and improve its shelf life. Ahypotonic saline solution enhances osmosis into the cellular structurewhich contributes significantly to the dilution and extraction of thegeosmin content. An organic acid additive, such as 1-glutamic orascorbic acid, also decomposes the geosmin. The same organic acidadditive or another chosen organic acid may also be used to re-establishthe integrity of the cellular membrane. In addition, a yeast product maybe added to enhance the tissue flavor.

It should be understood from the present invention that any combinationof the mechanical and chemical aspects of the present invention may beused without departing from the scope of the invention. In oneembodiment, the process produces a cleaner, whiter catfish withcontrolled hydration during the vacuum tumbling process. In addition tosignificantly reducing the off-flavor problem, the process also reducestotal fat, cholesterol, and triglyceride content of the catfish, andprolongs shelf life through bacterial lysis. The several mechanical andchemical aspects of the present invention combine to produce catfish ofsuperior quality and consistency.

FIG. 1 illustrates the process steps and components of processor 10. Theoperation of processor 10 will be described with reference to catfish,but it should be understood that processor 10 may be used successfullywith any other appropriate food product. The process steps performed inprocessor 10 are shown in a particular order but may be performed in adifferent sequence without departing from the scope of the presentinvention. In addition, process steps may be performed at a singlelocation or multiple locations.

Catfish 12 of varying sizes are caught and sorted based on size,appearance, or other appropriate characteristic to select sorted catfish14 appropriate for processing by processor 10. Sorted catfish 14 arethen de-headed, eviscerated, and de-boned by an automatic skinner-filletmachine 16. Skin, fins, and other similar material may be diverted forsale to the animal food preparation industry. The resulting fillet 18from automatic skinner-fillet machine 16 is then ready for the variousprocessing steps performed by processor 10. The following stepsperformed in processor 10 will be described with reference to ade-headed, de-boned, and eviscerated fillet, but it should be understoodthat the present invention contemplates processing animal products thatinclude bones, internal organs, and other portions not intended forconsumption.

The membranes of fillet 18 are perforated by perforator 20 to allowbetter tissue access during processing. Perforator 20 may be a singleroller with perforating protrusions or a pair of rollers as shown inFIG. 1. Perforated fillet 22 is then weighed at scale 24 and analyzedfor fat or lipid content by analyzer 26. Both scale 24 and analyzer 26may transmit data regarding the weight and fat content of perforatedfillet 22 to computer 28 over data collection lines 30. It should beunderstood that analyzer 26 may also be adapted to measure cholesterol,triglycerides, or any other monitored component of fillet 22.

Perforated fillets 22 are loaded into vacuum tumbler 32 for processing.Vacuum tumbler 32 comprises a cylindrical drum 34 mounted to rotateabout a central axis. Affixed to the internal wall of cylindrical drum34 are ribs 36 extending substantially parallel to the axis of rotationof cylindrical drum 34. Door 38 provides access to the inside ofcylindrical drum 34, and drain 39 allows filling and draining ofcylindrical drum 34 with processing solution 48, described below.

Motor 40 rotates cylindrical drum 34 either directly or through anappropriate transmission 42 using gears, pulleys, belts, or otherappropriate members. It should be understood that the present inventioncontemplates any motor or engine 40 optionally coupled with anappropriate transmission 42 that can impart a rotational velocity tocylindrical drum 34. Vacuum source 44 is also connected to cylindricaldrum 34 through vacuum source access port 46. Vacuum source 44 may beremovable from vacuum source access port 46 to allow for free rotationof cylindrical drum 34. Vacuum source 44 operates to reduce the internalpressure of cylindrical drum 34. In one embodiment, vacuum source 44reduces the internal pressure of cylindrical drum 34 by at least twentyfive inches of mercury (Hg). The specific vacuum level may be adjustedbased on the age and condition of the fish, as well as other factors.Both motor 40 and vacuum source 44 are connected to computer 28 throughcontrol lines 47.

Partially filling the inside of cylindrical drum 34 is processingsolution 48. In one embodiment, processing solution 48 comprises: (i)water (H₂ O) in an amount approximately equal by weight to fillets 22,and (ii) sodium chloride in an amount no more than 0.9 percent of theweight of fillets 22. To increase the osmotic absorption of processingsolution into the membranes of fillets 22, a hypotonic saline solutionof approximately 0.45 percent sodium chloride (NaCl) may be used.Although the amount of processing solution 48 should be approximatelyequal to the weight of fillets 22, the amount may vary without departingfrom the scope of the present invention.

An organic acid may also be added in an amount sufficient to adjust thepH of processing solution 48 to a value preferably from 4.5 to 5.5, butin any event less than 8.0. The organic acid may be 1-glutamic acid,ascorbic acid, or any other appropriate acid that may facilitate geosmindecomposition. Yeast may also be added to processing solution 48 in anamount of approximately 0.1 percent of the weight of fillets 22. Theyeast is added to enhance the flavor of perforated fillets 22.

After loading perforated fillets 22 and processing solution 48, andafter creating a partial vacuum within cylindrical drum 34 by vacuumsource 44, cylindrical drum 34 is rotated by motor 40 at a predeterminedrate and for a predetermined time. In one embodiment, cylindrical drum34 is rotated at eight revolutions per minute for eight to twelveminutes. After the predetermined time for tumbling, the partial vacuumis released and fillets 22 may be drained, rinsed, and re-drained. Thedraining and rinsing steps (not shown) may be performed before or afterremoving fillets 22 from vacuum tumbler 32.

Processed fillets 50 may be weighed by scale 24 and analyzed for fat orlipid content by analyzer 26. As described above, analyzer 26 may beadapted to measure cholesterol, triglycerides, or other monitoredcomponent of processed fillets 50. Processed fillets 50 may weigh tenpercent or more than unprocessed fillets 22 due to the hydration processduring tumbling. Processed fillets 50 may contain significantly lessfat, cholesterol, and triglycerides than unprocessed fillets 22 due tothe decomposition and extraction process during tumbling.

Flash chromatography (not shown) may be used to analyze each processedfillet 50 for bacteria count. Processed fillets are then sorted, andsorted fillets 52 are placed in appropriate packaging 54. Packaging 54may be either ice packing for fresh production or individualquick-freeze processed packing for frozen product packaging.

Computer 28 receives data from scale 24 and analyzer 26 over datacollection lines 30. As depicted by the pair of scales 24 and the pairof analyzers 26 in FIG. 1, data may be collected on unprocessed fillets22 or processed fillets 50. Computer 28 may then process this data andissue control signals to motor 40 and vacuum source 44 over controllines 47. Computer 28 further comprises a timer for determining elapsedtime, a memory for storing data received from scale 24 and analyzer 26,and a control module for processing control signals to send to motor 40and vacuum source 44 in response to stored data and elapsed time.

FIG. 2 is a flow diagram that illustrates the sequence of process stepsperformed by processor 10, including the information flow betweencomputer 28, scale 24, analyzer 26, motor 40, and vacuum source 44. Itshould be understood from the present invention, that the process stepsin FIG. 2 may be performed in various sequences without departing fromthe scope of the present invention.

Processing begins with a sort of the animal products to be processed atblock 100. The animal products are filleted at block 102 and thesefillets are perforated at block 104. The perforated fillets are thenweighed at block 106 and their fat content determined at block 108.

The following group of steps designated by dashed block 110 preparesvacuum tumbler 32 of FIG. 1 for processing. The fillets are loaded intothe vacuum tumbler at block 112 and the processing solution is added atblock 114. The vacuum tumbler is then evacuated to create a partialvacuum at block 116. The vacuum tumbler, properly loaded and evacuated,is then rotated at a predetermined rate for a predetermined amount oftime at block 118.

In one embodiment of the present invention, data generated at block 106during weighing and block 108 during analyzing the fat content are fedforward to determine the amount and composition of processing solutionadded at block 114, the level of the partial vacuum created at block116, and the predetermined rate and time to tumble the animal productsperformed at block 118. This operation indicates an open loop systemwhere computer 28 receives data on unprocessed fillet 22 from scale 24and analyzer 26 and controls motor 40 and vacuum source 44 in responseto that data. The information flow of an open loop system fordetermining the operating characteristics of the vacuum tumbler areshown by feed-forward lines 120.

After tumbling for a predetermined amount of time at block 118, theprocess continues at block 122 where the fat content of processedfillets is determined. The processed fillets are also weighed at block124. In another embodiment of the present invention, data determined atblocks 122 and 124 may be fed back over feedback lines 126 to initiate are-tumble at block 118. A re-tumble may be based on fat contentdetermined at block 122 or relative hydration indicated by weightdetermined at block 124. Fish fillets are then sorted at block 128 andpackaged at block 130.

The present invention described with reference to FIGS. 1 and 2 has beenused successfully to process catfish. Objective studies on the effect ofthe processing focus on two types of analysis. One analysis comparesunprocessed catfish tissue to processed catfish tissue and indicates anincrease in moisture content and reduced fat content due to the vacuumtumbling. A significant decrease in the fat content was measured for allvarieties of catfish product. Another objective analysis indicates thatthe processing solution after tumbling contains significant amounts offat, cholesterol, and triglycerides.

Although the present invention has been described with severalembodiments, various changes and modifications may be suggested to oneskilled in the art. In particular, the present invention was describedwith reference to catfish, but may apply to other animal products withlittle alteration and similar results. Furthermore, the presentinvention contemplates several process steps which may be performed inthe sequence described, or in an alternative sequence without departingfrom the scope of the present invention. The present invention isintended to encompass such changes and modifications as fall within thescope of the appended claims.

What is claimed is:
 1. A method for extracting off-flavor componentsfrom animal products, comprising:perforating the membranes of animalproducts; loading the animal products into a vacuum tumbler; filling thetumbler to a predetermined level with a hypotonic saline solution, thehypotonic saline solution comprising water and sodium chloride in anamount no more than 0.9 percent of the weight of the water, thehypotonic saline solution being operable to enhance osmosis into thecellular structure of the animal products; withdrawing air from thetumbler to create a partial vacuum; rotating the tumbler for apredetermined time to expose the animal products to the hypotonic salinesolution and the partial vacuum under conditions sufficient to extractoff-flavor components from the animal products and to increase osmoticabsorption of the solution into the membranes of the animal products;removing the animal products from the tumbler after the predeterminedtime; and then packaging the animal products.
 2. The method of claim 1,further comprising the step of measuring the fat content of the animalproducts prior to loading the animal products into the tumbler.
 3. Themethod of claim 1, further comprising the step of measuring the fatcontent of the animal products after rotating the tumbler for thepredetermined time.
 4. The method of claim 1, further comprising thefollowing steps performed prior to loading the animal products into thetumbler:measuring the fat content of the animal products; and weighingthe animal products.
 5. The method of claim 1, further comprising thefollowing steps performed after rotating the tumbler for thepredetermined time:measuring the fat content of the animal products; andweighing the animal products.
 6. The method of claim 1, wherein the stepof filling the tumbler to a predetermined level with a hypotonic salinesolution comprises filling the tumbler with an amount of hypotonicsaline solution approximately equal by weight to the animal products. 7.The method of claim 1, wherein the hypotonic saline solution furthercomprises an organic acid in an amount sufficient to adjust the pH ofthe solution to a value of less than 7.0.
 8. The method of claim 1,wherein the step of withdrawing air from the tumbler to create a partialvacuum reduces the internal pressure of the tumbler by at least 25inches of mercury.
 9. The method of claim 1, further comprising the stepof analyzing the animal products for bacteria after rotating the tumblerfor the predetermined time.
 10. The method of claim 1, wherein theanimal products gain no more than fifteen percent by weight afterrotating the tumbler for the predetermined time.
 11. The method of claim1, further comprising the step of rinsing the animal products afterrotating the tumbler for the predetermined time.
 12. A method forextracting off-flavor components from animal products,comprising:loading animal products into a vacuum tumbler filled with apredetermined level of hypotonic saline solution, the hypotonic salinesolution comprising water and sodium chloride in an amount no more than0.9 percent of the weight of the water, the hypotonic saline solutionbeing operable to enhance osmosis into the cellular structure of theanimal products; and then rotating the tumbler for a predetermined timeto expose the animal products to the hypotonic saline solution and to apartial vacuum under conditions sufficient to extract off-flavorcomponents from the animal products and to increase osmotic absorptionof the solution into the cellular structure of the animal products. 13.The method of claim 12, further comprising the step of perforating themembranes of the animal products before loading the animal products intothe tumbler.
 14. The method of claim 12, further comprising the step ofwithdrawing air from the tumbler to create a partial vacuum beforerotating the tumbler for a predetermined time.
 15. The method of claim12, wherein the predetermined amount of hypotonic saline solution isapproximately equal by weight to the weight of the animal products. 16.The method of claim 12, wherein the processing solution furthercomprises an organic acid in an amount sufficient to adjust the pH ofthe solution to a value of less than 7.0.
 17. The method of claim 12,further comprising the step of measuring the fat content of the animalproducts prior to loading the animal products into the tumbler.
 18. Themethod of claim 12, further comprising the step of measuring the fatcontent of the animal products after rotating the tumbler for apredetermined time.
 19. The method of claim 12, further comprising thestep of analyzing the animal products for bacteria after rotating thetumbler for a predetermined time.
 20. The method of claim 12, whereinthe animal products gain no more than fifteen percent by weight afterrotating the tumbler for the predetermined time.